As cars are a common transportation vehicle and portable electronic devices, such as, smart phone and tablet PC, become a mainstream communication and entertainment gadget, the use of portable devices in cars creates a demand in auxiliary apparatus for using portable devices in cars. While the driver using portable device may pose potential hazard, the passenger using portable device inside vehicle is a good way to stay entertained.
To provide good riding environment for passengers, some manufacturers developed auxiliary apparatus applicable to seatback inside vehicle. These known auxiliary apparatuses are often fastened to the rods supporting the headrest on the seatback of the front seat for holding portable electronic device, such as, tablet, for viewing. However, such auxiliary apparatus is not convenient for users to operate the device, such as, playing games or typing. Furthermore, the majority of these known auxiliary apparatuses can only fit a specific size, which causes further inconvenience for users with devices of different sizes.